The present invention relates to a system for dispensing a liquid, the system comprising both a receptacle and apparatus for refilling the receptacle with compressed air, the bottom of the receptacle being provided with a filling valve.
Attempts are being made at present to replace aerosol receptacles that contain a propellant gas constituted by a liquefied gas, with aerosol receptacles using compressed air as the propellant gas.
The use of compressed air raises a problem of independence if it is desired to maintain constant quality, and it turns out to be necessary to refill the receptacle several times in order to be able to dispense in satisfactory manner all of the liquid contained in the receptacle, the propellant gas being dispensed together with the liquid.
International patent application WO 94/03380 discloses a system for dispensing a liquid, the system comprising both a receptacle provided with a filling valve and apparatus enabling the receptacle to be refilled with compressed air.
The filling valve is connected to a tube that emerges above the surface of the liquid, so as to avoid producing a foam inside the receptacle when the receptacle is refilled with compressed air.
The filling valve is also relatively complex since it must be capable of providing sealing not only for compressed air but also for the liquid contained in the receptacle.
International patent application WO 91/01257 discloses a system of the same type as that described in application WO 94/03380, the filling valve being preferably fitted with a tube that emerges above the surface of the liquid. The filling valve preferably has a first gasket which opens when a filling endpiece is inserted, and a second gasket which opens under the pressure of air escaping from the filling endpiece, and it presents a structure that is relatively complex.
U.S. Pat. No. 5,343,904 discloses a system similar to those described in the above-mentioned international applications, in which the filling valve has a ball and a O-ring. The filling endpiece has a diameter that is relatively large and carries an O-ring. A relatively complex lever mechanism engages the filling valve during filling, in order to prevent the receptacle from moving.
The invention seeks in particular to remedy all or part of the drawbacks of known dispensing systems, and in particular seeks to propose a system of structure that is relatively simple and that operates reliably.
The novel system of the invention comprises both a receptacle and apparatus for refilling the receptacle with compressed air, the receptacle being provided with a filling valve, wherein the fluid to be dispensed and the air under pressure are contained inside the receptacle in separate manner in different spaces.
By means of the invention, it is possible to use a filling valve which is relatively simple in structure since it does not come into contact with the liquid.
In addition, it does not need to be connected to a tube since there is no risk of foaming occurring while the receptacle is being filled with gas.
Preferably, the fluid is a liquid contained in a flexible bag inside the receptacle.
Also preferably, the receptacle is provided with a valve enabling the liquid to be dispensed, said valve having at least three functionally different positions, namely: a rest position; a position enabling air to be dispensed on its own; and a position enabling a mixture of air and liquid to be dispensed.
Also preferably, the filling valve is made solely out of elastomer, preferably by molding a single piece.
The valve then preferably presents a structure that is less complex than the filling valves of known dispensing systems, as mentioned above.
The apparatus enabling the receptacle to be refilled with compressed air advantageously comprises a compressor and an endpiece connected to the outlet of the compressor and arranged to engage in the valve of the receptacle.
Preferably, the apparatus enabling the receptacle to be refilled with compressed air includes a moving member provided with a passage for the endpiece, the moving member and the endpiece being arranged in such a manner that the endpiece engages in the valve of the receptacle in response to the moving member being pushed down.
Preferably, for a filling valve having an end wall, the length of the endpiece is selected so that it does not reach the end wall of the filling valve when the moving member is pushed down, the endpiece being engaged over only two-thirds of the length of the valve, for example.
Preferably, the endpiece remains engaged in the moving member whatever the position of the moving member, and in particular in the absence of a receptacle.
This prevents the endpiece being damaged by the receptacle when the receptacle is put into place on the moving member.
Preferably, the moving member is returned into an initial position by resilient return means.
The friction between the endpiece and the filling valve can be selected in such a manner that the endpiece is clamped sufficiently by the filling valve to retain the receptacle against the return action of the resilient return means.
In other words, the friction between the filling valve and the endpiece holds the moving member down, thereby presenting the advantage of providing the system with structure that is much simpler that that described in above-mentioned U.S. Pat. No. 5,343,904.
Preferably, the moving member is arranged in such a manner as to protect the endpiece in the absence of a receptacle.
In particular, in the absence of a receptacle placed on the moving member, the endpiece does not project beyond it, so that the moving member provides effective protection for the endpiece in the absence of the receptacle.
Advantageously, the apparatus enabling the receptacle to be refilled with compressed air has a detector suitable for detecting that the moving member and arranged to cause the compressor to be switched on when the moving member is down.
Thus, the compressor is set automatically into operation by putting the receptacle into the filling position.
By way of example, the detector can include a microswitch.
In a particular embodiment, the apparatus is arranged in such a manner that the user must hold the moving member down throughout the entire time required for refilling the receptacle.
In which case, as soon as the user releases the receptacle, the moving member rises under the return action of the resilient return means and the endpiece disengages from the valve of the receptacle.
The return of the moving member into its initial position is advantageously detected so that the operation of the compressor is automatically interrupted at that moment.
In a preferred embodiment, the apparatus includes retaining means arranged to hold the moving member down either directly or indirectly against the return action of the resilient return means, so long as a predetermined condition is satisfied, said predetermined condition corresponding, for example, to the pressure inside the receptacle being below a predetermined value and/or to the fact that the compressor is in operation.
In a particular embodiment, the apparatus includes a pressure controller at the outlet from the compressor.
The pressure controller is advantageously used to stop operation of the compressor when the pressure inside the receptacle reaches a predetermined value, corresponding to the end of filling with compressed air.
The above-mentioned retaining means for holding the moving member down throughout the duration of filling advantageously comprise at least one suction cup connected to the inlet of the compressor.
In a particular embodiment, the or each suction cup is positioned in such a manner that the moving member comes into contact therewith when it is pushed down.
So long as the compressor is in operation, the or each suction cup can thus participate in holding the moving member in its down position, due to the suction that exists at the inlet to the compressor.
When the pressure in the receptacle reaches a predetermined value, corresponding to the end of the receptacle being filled with compressed air, the operation of the compressor is interrupted.
The partial vacuum that exists at the inlet to the compressor ceases, such that the adhesion of the or each suction cup on the moving member also ceases and the moving member can return to its initial position under the return action of the resilient return means.
The return movement of the moving member towards its initial position pushes away the receptacle and the endpiece is disengaged from the valve.
In another particular embodiment, the or each suction cup comes into contact with the receptacle when the moving member is pushed down. The moving member then advantageously includes openings enabling the or each suction cup to come into contact with the bottom of the receptacle when the receptacle is standing on the moving member and the moving member is down.
Thus, the moving member is held down against the action of the resilient return means by the or each suction cup adhering to the receptacle, due to the suction that exists at the inlet to the compressor while the compressor is in operation.
If the receptacle is withdrawn, the moving member rises under the effect of the resilient return means.
This upward movement of the moving member is advantageously detected so as to interrupt operation of the compressor.
Advantageously, the apparatus has three suction cups that are uniformly distributed angularly around the endpiece.
In a particular embodiment, the compressor is connected by a pipe to an air intake which is arranged in such a manner as to give rise to head loss.
Advantageously, said head loss is selected so that the suction existing at the inlet of the compressor is strong enough to enable the suction cup(s) to exert the desired force on the moving member or the receptacle.
When the bottom of the receptacle is outwardly concave, the top surface of the moving member advantageously presents a dome arranged to favor proper positioning of the receptacle relative to the moving member.